My friends and I put together a comic video about the adventures of one of our teachers. Most of the scenes are based on stories he's told us in class, but some are things we just dreamt up. Would it be illegal to show this video due to its content? We represented our teacher using plastic action figures, but we used his last name.
While your creativity is impressive, you should be wary of posting this video. It might get you into both academic trouble (if your school forbids this sort of satire) as well as potential legal trouble.
If your teacher (or his lawyer) believes that you have damaged his reputation, he could sue you for defamation or libel. To win, he would need to show that you made statements that were untrue and that caused others to think less of him, thus harming his reputation. He will not have much trouble proving that he was the subject of the video, since you used his name.
However, it is not easy to determine whether your video violates defamation and libel laws. For example, you might think it was a compliment to represent your teacher with a plastic action figure. But your teacher's lawyer may argue that his new plastic embodiment is unattractive or appears "stiff." Although proving that one's reputation has been damaged is not easy, his attorney might focus on the negative commentary contained in your video. If you took footage of him personally without his consent, this could violate his right of privacy as well as his right of publicity.
You could run into another problem if your video is successful and generates money. Your teacher could sue you for using his name for a commercial purpose, under these same right of publicity laws.
Here's how the professional moviemakers deal with this type of dilemma: They either get a signed "release" from the person who is the subject of the film or they have an attorney review the film before it is shown publicly. By signing a "release," your teacher would be consenting to the use of his name or image. Of course, if your teacher is incensed by the video, he will not be inclined to sign anything you send his way, other than a transfer out of his class. But as a student, you should probably avoid creating any media that angers a member of the faculty.
You can find standard form releases in Nolo's book Getting Permission: How to License & Clear Copyrighted Materials Online & Off, by Richard Stim.